Numerous disengageable fastening systems are known, for example, threaded fastening systems including bolts and optionally associated nuts. For fixating and disengaging the fastening typically tools are provided that are adapted to the particular fastening system. These tools include a tool operating surface which is configured corresponding to a tool engagement surface at least at one of the fastener elements of the fastening system. On bolts the tool engagement surface forms the drive.
With respect to fastening systems of the type recited supra there is a strong need to configure them so that unauthorized disengagement is directly evident or prevented entirely.
For the latter variant new geometries of bolt drives were developed in the past in order to prevent that unauthorized persons are able to disengage and fixate these fastening systems at all with tools at hand. Among these are the tri-wing-drive, the Torq Set drive, the Pentalob drive and the Torx® Tamper drive. These configurations have the disadvantage that standard tools for everybody are available for these drives after a certain time period so that manipulations by unauthorized persons are thus possible without detection.
Another variant is described in DE 696 33 832 T2 and US 2008/0205974 A1. They describe a fastening system with bolts and nuts in which the bolts have notches and the nuts have spring elastic prongs which slide over the notches in a fixation direction, but interlock in the notches in a disengagement direction unless appropriate tools are provided so that a disengagement without appropriate tools is impossible. This variant unfortunately has a very complicated configuration which renders operations very difficult also for authorized persons. Additionally accordingly configured standard tools are typically available also for unauthorized persons after a certain time period.
In this group there are also tear off bolts which facilitate fixation but which can only be disengaged with special tools after the drive is torn off. There are one way bolts with a one way drive which can be fixated with a standard tool but can only be disengaged with a special tool. These variants in turn are cumbersome and the special tools can also be obtained by unauthorized persons.
For the variant cited first bolts, nuts and similar are used which indicate a manipulation directly. Thus, for example a seal with lacquer or a sticker can be applied which has to be destroyed during disengagement. Thus, also circumferential sealing elements can be used which also have to be destroyed first in order to provide disengagement as it is known for screw tops for beverage bottles. These configurations in turn are complicated to use and on the other hand side the seal elements can only be used once.